Optical Nonlinear Absorption And Photo-physical Mechanism Of Anthracene Derivatives

In recent decades,organic materials have been used in many practical applications due to their flexible structure,low cost,fast response time and large nonlinear optical?NLO?response,such as all-optical switches,organic light-emitting diodes and optical storage.The investigation of the effects of structural changes on the physical parameters of these materials not only helps to understand the relationship between structure and properties,but also provides insight into the mechanism of interaction between laser and media.It can provide a reference for the development of better nonlinear optical materials in the futureTwo novel anthracene derivatives,Ant₁ and Ant₂,with different ?-bridge lengths were designed and synthesized to investigate their optical nonlinearities.The broadband femtosecond Z-scan results show that Ant 1 and Ant₂ exhibit broadband reverse saturable absorption,and the reverse saturable absorption of Ant₂ is stronger than that of Ant₁.The mechanisms of reverse saturable absorption for both compounds are two-photon absorption and two-photon induced excited-state absorption.Combined with the results of quantum chemical calculations,the reverse saturable absorption of Ant₂ is superior to that of Ant 1 because the increase in the number of ethylene double bonds for Ant 2 caused a better molecular planarity.Femtosecond transient absorption spectra experiments have carried out to investigated the dynamics of the two materials,and the results reveal the relaxation process of particles from the singlet local excited state to the charge transfer state.By comparing the optical limiting properties of both materials,it can be found that Ant₂ performs better optical limiting,and it implies that Ant₂ has potential application in the optical limiting.The results of this article reveal that extending the ?-bridge to adjust the molecular planarity via increasing the amount of ethylene has a great effect on the optical nonlinear properties and photo-physical processes.It may provide reference for the design of anthracene-based nonlinear optical materials with excellent properties in the future.